1. Field of the Invention
The present invention relates to a gate valve and more particularly to a gate valve for use in a processing device for processing a semiconductor wafer or the like.
2. Description of the Prior Art
In a processing device for processing a semiconductor wafer, a liquid crystal substrate or the like, the wafer or the substrate is inserted into or taken out from one of many kinds of processing rooms through passages each having a gate valve. It is necessary to prevent as much as possible foreign matters from entering into the processing room.
Such gate valve is described in the Japanese Patent Laid-Open No. 156781/83. In such gate valve, a valve disc is moved up and down while separating from a valve seat, and the valve disc is brought into contact with the valve seat by urging the side surface of the valve disc toward the valve seat when the valve disc is positioned to face to the valve seat.
In said gate valve heretofore in use, however, passage, so that foreign matters are unavoidably produced from said movable parts and entered into the processing room.